User u = new User();
Type t = typeof(User);
u is User -> returns true
u is t -> compilation error
How do I test if some variable is of some type in this way?
This question is related to
c#
reflection
types
The other answers all contain significant omissions.
The is operator does not check if the runtime type of the operand is exactly the given type; rather, it checks to see if the runtime type is compatible with the given type:
class Animal {}
class Tiger : Animal {}
...
object x = new Tiger();
bool b1 = x is Tiger; // true
bool b2 = x is Animal; // true also! Every tiger is an animal.
But checking for type identity with reflection checks for identity, not for compatibility
bool b5 = x.GetType() == typeof(Tiger); // true
bool b6 = x.GetType() == typeof(Animal); // false! even though x is an animal
or with the type variable
bool b7 = t == typeof(Tiger); // true
bool b8 = t == typeof(Animal); // false! even though x is an
If that's not what you want, then you probably want IsAssignableFrom:
bool b9 = typeof(Tiger).IsAssignableFrom(x.GetType()); // true
bool b10 = typeof(Animal).IsAssignableFrom(x.GetType()); // true! A variable of type Animal may be assigned a Tiger.
or with the type variable
bool b11 = t.IsAssignableFrom(x.GetType()); // true
bool b12 = t.IsAssignableFrom(x.GetType()); // true! A
You need to see if the Type of your instance is equal to the Type of the class. To get the type of the instance you use the GetType() method:
u.GetType().Equals(t);
or
u.GetType.Equals(typeof(User));
should do it. Obviously you could use '==' to do your comparison if you prefer.
GetType() exists on every single framework type, because it is defined on the base object type. So, regardless of the type itself, you can use it to return the underlying Type
So, all you need to do is:
u.GetType() == t
In order to check if an object is compatible with a given type variable, instead of writing
u is t
you should write
typeof(t).IsInstanceOfType(u)
Source: Stackoverflow.com